diff --git a/test/plantuml-preview-test.el b/test/plantuml-preview-test.el
index 8dd9f44..3bcd862 100644
--- a/test/plantuml-preview-test.el
+++ b/test/plantuml-preview-test.el
@@ -8,15 +8,18 @@
 
 ;;; Code:
 
-(defun assert-preview (puml output)
+(defun assert-preview (puml output &optional format)
+  (unless format (setq-local plantuml-output-type "utxt"))
   (plantuml-preview-string 42 (read-test-file puml))
-  (sleep-for 2)
+  (sleep-for 3)
   (should (equal (read-test-file output) (read-preview-buffer))))
 
 (ert-deftest preview-test ()
   (setq-local plantuml-jar-path plantuml-test-jar-path)
   (setq-local plantuml-output-type "utxt")
-  (assert-preview "a-b.puml" "a-b.txt"))
+
+  (assert-preview "a-b.puml" "a-b.txt")
+  (assert-preview "unicode.puml" "unicode.txt"))
 
 (provide 'plantuml-mode-preview-test)
 
diff --git a/test/resources/a-b.png b/test/resources/a-b.png
new file mode 100644
index 0000000..c2900f8
Binary files /dev/null and b/test/resources/a-b.png differ
diff --git a/test/resources/unicode.png b/test/resources/unicode.png
new file mode 100644
index 0000000..cc6cb03
Binary files /dev/null and b/test/resources/unicode.png differ
diff --git a/test/resources/unicode.puml b/test/resources/unicode.puml
new file mode 100644
index 0000000..3fac1a4
--- /dev/null
+++ b/test/resources/unicode.puml
@@ -0,0 +1,5 @@
+@startuml
+
+lang -> 日本語
+
+@enduml
diff --git a/test/resources/unicode.txt b/test/resources/unicode.txt
new file mode 100644
index 0000000..bed17ca
--- /dev/null
+++ b/test/resources/unicode.txt
@@ -0,0 +1,8 @@
+     ┌────┐          ┌──────┐
+     │lang│          │日本語│
+     └──┬─┘          └───┬──┘
+        │                │ 
+        │────────-----──>│ 
+     ┌──┴─┐          ┌───┴──┐
+     │lang│          │日本語│
+     └────┘          └──────┘